Search for "ring closure" in Full Text gives 293 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
Graphical Abstract
Figure 1: Energy diagram of a two-state photoswitch. Figure 1 was redrawn from [2].
Figure 2: Example of the absorption spectra of the isomers of a photoswitch with most efficient irradiation w...
Scheme 1: Photoswitch classes described in this review.
Figure 3: Azoheteroarenes.
Scheme 2: E–Z Isomerisation (top) and mechanisms of thermal Z–E isomerisation (bottom).
Scheme 3: Rotation mechanism favoured by the electron displacement in push–pull systems. Selected examples of...
Figure 4: A) T-shaped and twisted Z-isomers determine the thermal stability and the Z–E-PSS (selected example...
Figure 5: Effect of di-ortho-substitution on thermal half-life and PSS.
Figure 6: Selected thermal lifetimes of azoindoles in different solvents and concentrations. aConcentration o...
Figure 7: Aryliminopyrazoles: N-pyrazoles (top) and N-phenyl (bottom).
Scheme 4: Synthesis of symmetrical heteroarenes through oxidation (A), reduction (B), and the Bayer–Mills rea...
Scheme 5: Synthesis of diazonium salt (A); different strategies of azo-coupling: with a nucleophilic ring (B)...
Scheme 6: Synthesis of arylazothiazoles 25 (A) and heteroaryltriazoles 28 (B).
Scheme 7: Synthesis of heteroarylimines 31a,b [36-38].
Figure 8: Push–pull non-ionic azo dye developed by Velasco and co-workers [45].
Scheme 8: Azopyridine reported by Herges and co-workers [46].
Scheme 9: Photoinduced phase transitioning azobispyrazoles [47].
Figure 9: Diazocines.
Scheme 10: Isomers, conformers and enantiomers of diazocine.
Scheme 11: Partial overlap of the ππ* band with electron-donating substituents and effect on the PSS. Scheme 11 was ada...
Figure 10: Main properties of diazocines with different bridges. aMeasured in n-hexane [56]. bMeasured in THF. cMe...
Scheme 12: Synthesis of symmetric diazocines.
Scheme 13: Synthesis of asymmetric diazocines.
Scheme 14: Synthesis of O- and S-heterodiazocines.
Scheme 15: Synthesis of N-heterodiazocines.
Scheme 16: Puromycin diazocine photoswitch [60].
Figure 11: Indigoids.
Figure 12: The main representatives of the indigoid photoswitch class.
Scheme 17: Deactivation process that prevents Z-isomerisation of indigo.
Figure 13: Stable Z-indigo derivative synthesised by Wyman and Zenhäusern [67].
Figure 14: Selected examples of indigos with aliphatic and aromatic substituents [68]. Dashed box: proposed π–π in...
Scheme 18: Resonance structures of indigo and thioindigo involving the phenyl ring.
Scheme 19: Possible deactivation mechanism for 4,4'-dihydroxythioindigo [76].
Scheme 20: Effect of different heteroaryl rings on the stability and the photophysical properties of hemiindig...
Figure 15: Thermal half-lives of red-shifted hemithioindigos in toluene [79]. aMeasured in toluene-d8.
Scheme 21: Structures of pyrrole [81] and imidazole hemithioindigo [64].
Figure 16: Examples of fully substituted double bond hemithioindigo (left), oxidised hemithioindigos (centre),...
Scheme 22: Structure of iminothioindoxyl 72 (top) and acylated phenyliminoindolinone photoswitch 73 (bottom). ...
Scheme 23: (top) Transition states of iminothioindoxyl 72. The planar transition state is associated with a lo...
Scheme 24: Baeyer–Drewsen synthesis of indigo (top) and N-functionalisation strategies (bottom).
Scheme 25: Synthesis of hemiindigo.
Scheme 26: Synthesis of hemithioindigo and iminothioindoxyl.
Scheme 27: Synthesis of double-bond-substituted hemithioindigos.
Scheme 28: Synthesis of phenyliminoindolinone.
Scheme 29: Hemithioindigo molecular motor [85].
Figure 17: Arylhydrazones.
Scheme 30: Switching of arylhydrazones. Note: The definitions of stator and rotor are arbitrary.
Scheme 31: Photo- and acidochromism of pyridine-based phenylhydrazones.
Scheme 32: A) E–Z thermal inversion of a thermally stable push–pull hydrazone [109]. B) Rotation mechanism favoured...
Scheme 33: Effect of planarisation on the half-life.
Scheme 34: The longest thermally stable hydrazone switches reported so far (left). Modulation of thermal half-...
Figure 18: Dependency of t1/2 on concentration and hypothesised aggregation-induced isomerisation.
Figure 19: Structure–property relationship of acylhydrazones.
Scheme 35: Synthesis of arylhydrazones.
Scheme 36: Synthesis of acylhydrazones.
Scheme 37: Photoswitchable fluorophore by Aprahamian et al. [115].
Scheme 38: The four-state photoswitch synthesised by the Cigáň group [116].
Figure 20: Diarylethenes.
Scheme 39: Isomerisation and oxidation pathway of E-stilbene to phenanthrene.
Scheme 40: Strategies adapted to avoid E–Z isomerisation and oxidation.
Scheme 41: Molecular orbitals and mechanism of electrocyclisation for a 6π system.
Figure 21: Aromatic stabilisation energy correlated with the thermal stability of the diarylethenes [127,129].
Figure 22: Half-lives of diarylethenes with increasing electron-withdrawing groups [128,129].
Scheme 42: Photochemical degradation pathway promoted by electron-donating groups [130].
Figure 23: The diarylethenes studied by Hanazawa et al. [134]. Increased rigidity leads to bathochromic shift.
Scheme 43: The dithienylethene synthesised by Nakatani's group [135].
Scheme 44: Synthesis of perfluoroalkylated diarylethenes.
Scheme 45: Synthesis of 139 and 142 via McMurry coupling.
Scheme 46: Synthesis of symmetrical derivatives 145 via Suzuki–Miyaura coupling.
Scheme 47: Synthesis of acyclic 148, malonic anhydride 149, and maleimide derivatives 154.
Figure 24: Gramicidin S (top left) and two of the modified diarylethene derivatives: first generation (bottom ...
Scheme 48: Pyridoxal 5'-phosphate and its reaction with an amino acid (top). The analogous dithienylethene der...
Figure 25: Fulgides.
Scheme 49: The three isomers of fulgides.
Scheme 50: Thermal and photochemical side products of unsubstituted fulgide [150].
Figure 26: Maximum absorption λc of the closed isomer compared with the nature of the aromatic ring and the su...
Scheme 51: Possible rearrangement of the excited state of 5-dimethylaminoindolylfulgide [153].
Figure 27: Quantum yields of ring closure (ΦE→C) and E–Z isomerisation (ΦE→Z) correlated with the increasing s...
Scheme 52: Active (Eα) and inactive (Eβ) conformers (left) and the bicyclic sterically blocked fulgide 169 (ri...
Scheme 53: Quantum yield of ring-opening (ΦC→E) and E–Z isomerisation (ΦE→Z) for different substitution patter...
Scheme 54: Stobbe condensation pathway for the synthesis of fulgides 179, fulgimides 181 and fulgenates 178.
Scheme 55: Alternative synthesis of fulgides through Pd-catalysed carbonylation.
Scheme 56: Optimised synthesis of fulgimides [166].
Scheme 57: Photoswitchable FRET with a fulgimide photoswitch [167].
Scheme 58: Three-state fulgimide strategy by Slanina's group.
Figure 28: Spiropyrans.
Scheme 59: Photochemical (left) and thermal (right) ring-opening mechanisms for an exemplary spiropyran with a...
Figure 29: Eight possible isomers of the open merocyanine according to the E/Z configurations of the bonds hig...
Scheme 60: pH-Controlled photoisomerisation between the closed spiropyran 191-SP and the open E-merocyanine 19...
Scheme 61: Behaviour of spiropyran in water buffer according to Andréasson and co-workers [180]. 192-SP in an aqueo...
Scheme 62: (left box) Proposed mechanism of basic hydrolysis of MC [184]. (right box) Introduction of electron-dona...
Scheme 63: Photochemical interconversion of naphthopyran 194 (top) and spirooxazine 195 (bottom) photoswitches...
Scheme 64: Synthesis of spiropyrans and spirooxazines 198 and the dicondensation by-product 199.
Scheme 65: Alternative synthesis of spiropyrans and spirooxazines with indolenylium salt 200.
Scheme 66: Synthesis of 4’-substituted spiropyrans 203 by condensation of an acylated methylene indoline 201 w...
Scheme 67: Synthesis of spironaphthopyrans 210 by acid-catalysed condensation of naphthols and diarylpropargyl...
Scheme 68: Photoswitchable surface wettability [194].
Figure 30: Some guiding principles for the choice of the most suitable photoswitch. Note that this guide is ve...
Beilstein J. Org. Chem. 2025, 21, 1561–1567, doi:10.3762/bjoc.21.119
Graphical Abstract
Figure 1: (a) Increased ring-strain from macrocyclic oligoarene to partially fused oligoarene and nanobelt. (...
Scheme 1: Synthesis of o-phenylene-pyrrole-thiophene hybrid macrocycles.
Figure 2: X-ray crystal structure of 4. Thermal ellipsoids are scaled to 50% probability level. Solvent molec...
Scheme 2: Synthesis of aza[5]helicene-incorporated macrocyclic heteroarene 5.
Figure 3: 1H NMR spectra of 5 in DMSO-d6 (a) at room temperature and (b) at 100 °C.
Figure 4: (a) X-ray crystal structure of 5; (left) top view, (right) side view. Thermal ellipsoids are scaled...
Figure 5: UV–vis absorption and emission spectra of (a) 4 and (b) 5 in DMSO.
Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113
Graphical Abstract
Scheme 1: Typical [3 + 2] cycloaddition (above) and trapping (below) reactions of thiocarbonyl S-methanides 1a...
Scheme 2: Ambident reactivity of 5-mercapto-1H-tetrazoles 4 towards dimethyl 2-arylcyclopropane dicarboxylate...
Scheme 3: Regioselectivity of [3 + 2] cycloadditions of diazomethane with adamantanethione (7a) [22,24,25], and sterica...
Scheme 4: The in situ generation of sterically crowded thiocarbonyl S-methanides 1c,d (via a 1,3-dipolar cycl...
Scheme 5: Reactions of the in situ-generated thiocarbonyl S-methanides 1 (from 1,3,4-thiadiazolines 2) with e...
Figure 1: (a) Molecular structure of the N-insertion product (thioaminal) 9i. Atoms are represented by therma...
Scheme 6: Stepwise mechanism of the competitive N- and S-insertion reactions between the in situ-generated th...
Scheme 7: Mechanism of the isomerization of initially formed thioaminals 9 to dithioacetals 10.
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
Graphical Abstract
Figure 1: Bond lengths and bond angles in oxetane at 140 K [2].
Figure 2: Analogy of 3-substituted oxetanes to carbonyl and gem-dimethyl groups [12].
Figure 3: Use of oxetanes in drug design – selected examples.
Figure 4: Examples of oxetane-containing natural products.
Scheme 1: Synthetic strategies towards construction of the oxetane ring.
Scheme 2: Overview of intramolecular Williamson etherification and competing Grob fragmentation.
Scheme 3: Synthesis of spiro-oxetanes via 1,4-C–H insertion and Williamson etherification.
Scheme 4: Use of phenyl vinyl selenone in the synthesis of spirooxindole oxetanes.
Scheme 5: Synthesis of bicyclic 3,5-anhydrofuranoses via double epoxide opening/etherification.
Scheme 6: Preparation of spirooxetanes by cycloisomerisation via MHAT/RPC.
Scheme 7: Oxetane synthesis via alcohol C–H functionalisation.
Scheme 8: Access to oxetanes 38 from α-acetyloxy iodides.
Scheme 9: The kilogram-scale synthesis of oxetane intermediate 41.
Scheme 10: Overview of the intramolecular opening of 3-membered rings.
Scheme 11: Synthesis of 4,7-dioxatricyclo[3.2.1.03,6]octane skeletons.
Scheme 12: Silicon-directed electrophilic cyclisation of homoallylic alcohols.
Scheme 13: Hydrosilylation–iodocyclisation of homopropargylic alcohols.
Scheme 14: Cu-catalysed intramolecular O-vinylation of γ-bromohomoallylic alcohols.
Scheme 15: Cu-catalysed intramolecular cross-coupling of hydroxyvinylstannanes.
Scheme 16: Isomerisation of oxiranyl ethers containing weakly carbanion-stabilising groups.
Scheme 17: Cyclisation of diethyl haloalkoxymalonates.
Scheme 18: Synthesis of oxetanes through a 1,5-HAT/radical recombination sequence.
Scheme 19: General approach to oxetanes via [2 + 2] cycloadditions.
Scheme 20: Synthesis of tricyclic 4:4:4 oxetanes through a photochemical triple cascade reaction.
Scheme 21: Iridium-catalysed Paternò–Büchi reaction between α-ketoesters and simple alkenes.
Scheme 22: Three-step synthesis of spirocyclic oxetanes 83 via Paternò–Büchi reaction, nucleophilic ring openi...
Scheme 23: Enantioselective Paternò–Büchi reaction catalysed by a chiral iridium photocatalyst.
Scheme 24: Synthesis of polysubstituted oxetanes 92 via Cu(II)-mediated formal [2 + 2] cycloadditions.
Scheme 25: Synthesis of alkylideneoxetanes via NHC- and DBU-mediated formal [2 + 2] cycloadditions.
Scheme 26: Use of sulphur-stabilised carbanions in ring expansions.
Scheme 27: Synthesis of α,α-difluoro(arylthio)methyl oxetanes.
Scheme 28: Ring expansion in an industrial synthesis of PF-06878031.
Scheme 29: Ring contraction of triflated 2-hydroxy-γ-lactones.
Scheme 30: Ring contraction in an industrial synthesis of PF-06878031.
Scheme 31: Photochemical ring contraction of 2,5-dihydrofurans by aryldiazoacetic acid esters.
Scheme 32: Synthesis of 3-oxetanones via O-H insertion of carbenes.
Scheme 33: Synthesis of phosphonate oxetanones via gold-mediated alkyne oxidation/O–H insertion.
Scheme 34: Syntheses and common derivatisations of 3-oxetanone.
Scheme 35: SN1 substitution of 3-aryloxetan-3-ols by thiols and alcohols.
Scheme 36: Fe–Ni dual-catalytic olefin hydroarylation towards 3-alkyl-3-(hetero)aryloxetanes.
Scheme 37: Synthesis of 3-aryloxetan-3-carboxylic acids.
Scheme 38: Decarboxylative alkylation of 3-aryloxetan-3-carboxylic acids.
Scheme 39: Synthesis of 3-amino-3-aryloxetanes via photoredox/nickel cross-coupling catalysis.
Scheme 40: Intermolecular cross-selective [2 + 2] photocycloaddition towards spirooxetanes.
Scheme 41: Synthesis of 3-aryl-3-aminooxetanes via defluorosulphonylative coupling.
Scheme 42: Two-step synthesis of amide bioisosteres via benzotriazolyl Mannich adducts 170.
Scheme 43: Functionalisation of oxetanyl trichloroacetimidates 172.
Scheme 44: Synthesis of oxetane-amino esters 176.
Scheme 45: Tandem Friedel–Crafts alkylation/intramolecular ring opening of 3-aryloxetan-3-ols.
Scheme 46: Synthesis of polysubstituted furans and pyrroles.
Scheme 47: Synthesis of oxazolines and bisoxazolines.
Scheme 48: Tandem, one-pot syntheses of various polycyclic heterocycles.
Scheme 49: Synthesis of 1,2-dihydroquinolines via skeletal reorganisation of oxetanes.
Scheme 50: Synthesis of benzoindolines and 2,3-dihydrobenzofurans and their derivatisations.
Scheme 51: Synthesis of polysubstituted 1,4-dioxanes.
Scheme 52: Preparation of various lactones via ring opening of oxetane-carboxylic acids 219.
Scheme 53: Tsuji-Trost allylation/ring opening of 3-aminooxetanes.
Scheme 54: Arylative skeletal rearrangement of 3-vinyloxetan-3-ols to 2,5-dihydrofurans.
Scheme 55: Reductive opening of oxetanes using catalytic Mg–H species.
Scheme 56: Opening of oxetanes by silyl ketene acetals.
Scheme 57: Rhodium-catalysed hydroacylation of oxetanes.
Scheme 58: Generation of radicals from oxetanes mediated by a vitamin B12-derived cobalt catalyst.
Scheme 59: Reductive opening of oxetanes by B–Si frustrated Lewis pairs.
Scheme 60: Zirconocene-mediated reductive opening of oxetanes.
Scheme 61: Enantioselective syntheses of small and medium-size rings using chiral phosphoric acids.
Scheme 62: Asymmetric synthesis of 2,3-dihydrobenzo[b]oxepines catalysed by a chiral scandium complex.
Scheme 63: Enantioselective synthesis of 1,3-bromohydrins under a chiral squaramide catalysis.
Scheme 64: Enantioselective opening of 2-aryl-2-ethynyloxetanes by anilines.
Scheme 65: Ru-catalysed insertion of diazocarbonyls into oxetanes.
Scheme 66: Ring expansion of oxetanes by stabilised carbenes generated under blue light irradiation.
Scheme 67: Expansion of oxetanes via nickel-catalysed insertion of alkynyltrifluoroborates.
Scheme 68: Nickel-catalysed expansion of oxetanes into ε-caprolactones.
Scheme 69: Expansion of oxetanes via cobalt-catalysed carbonyl insertion.
Scheme 70: Gold-catalysed intramolecular 1,1-carboalkoxylation of oxetane-ynamides.
Scheme 71: Expansion of oxetanes by stabilised sulphoxonium ylides.
Scheme 72: Cu-catalysed ring expansion of 2-vinyloxetanes by diazoesters.
Scheme 73: Total synthesis of (+)-oxetin.
Scheme 74: Total synthesis of racemic oxetanocin A.
Scheme 75: Total synthesis of (−)-merrilactone A.
Scheme 76: Total synthesis of (+)-dictyoxetane.
Scheme 77: Total synthesis of ent-dichrocephone B.
Scheme 78: Total synthesis of (−)-mitrephorone A.
Scheme 79: Total synthesis of (−)-taxol.
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
Graphical Abstract
Figure 1: a) Stone–Wales (red) and azulene (blue) defects in graphene; b) azulene and its selected resonance ...
Figure 2: Examples of azulene-embedded 2D allotropic forms of carbon: a) phagraphene and b) TPH-graphene.
Scheme 1: Synthesis of non-alternant isomers of pyrene (2 and 6) using dehydrogenation.
Scheme 2: Synthesis of non-alternant isomer 9 of benzo[a]pyrene and 14 of benzo[a]perylene using dehydrogenat...
Scheme 3: Synthesis of azulene-embedded isomers of benzo[a]pyrene (18 and 22) inspired by Ziegler–Hafner azul...
Figure 3: General strategies leading to azulene-embedded nanographenes: a) construction of azulene moiety in ...
Scheme 4: Synthesis of biradical PAHs possessing significant biradical character using oxidation of partially...
Scheme 5: Synthesis of dicyclohepta[ijkl,uvwx]rubicene (29) and its further modifications.
Scheme 6: Synthesis of warped PAHs with one embedded azulene subunit using Scholl-type oxidation.
Scheme 7: Synthesis of warped PAHs with two embedded azulene subunits using Scholl oxidation.
Scheme 8: Synthesis of azulene-embedded PAHs using [3 + 2] annulation accompanied by ring expansion.
Scheme 9: Synthesis of azulene-embedded isomers of linear acenes using [3 + 2] annulation accompanied by ring...
Scheme 10: Synthesis of azulene-embedded PAHs using intramolecular C–H arylation.
Scheme 11: Synthesis of azulene-embedded isomers of acenes using intramolecular C–H arylation.
Scheme 12: Synthesis of azulene-embedded PAHs using intramolecular condensations.
Scheme 13: Synthesis of azulene-embedded PAH 89 using palladium-catalysed [5 + 2] annulation.
Scheme 14: Synthesis of azulene-embedded PAHs using oxidation of substituents around the azulene core.
Scheme 15: Synthesis of azulene-embedded PAHs using the oxidation of reactive positions 1 and 3 of azulene sub...
Scheme 16: Synthesis of azulene-embedded PAHs using intramolecular C–H arylation.
Scheme 17: Synthesis of an azulene-embedded isomer of terylenebisimide using tandem Suzuki coupling and C–H ar...
Scheme 18: Synthesis of azulene embedded PAHs using a bismuth-catalyzed cyclization of alkenes.
Scheme 19: Synthesis of azulene-embedded nanographenes using intramolecular cyclization of alkynes.
Scheme 20: Synthesis of azulene-embedded graphene nanoribbons and azulene-embedded helicenes using annulation ...
Scheme 21: Synthesis of azulene-fused acenes.
Scheme 22: Synthesis of non-alternant isomer of perylene 172 using Yamamoto-type homocoupling.
Scheme 23: Synthesis of N- and BN-nanographenes with embedded azulene unit(s).
Scheme 24: On-surface synthesis of azulene-embedded nanographenes from benzenoid precursors via dehydrogenatio...
Scheme 25: On-surface synthesis of azulene-embedded nanographenes from benzenoid precursors.
Scheme 26: On-surface synthesis of azulene-embedded nanoribbons.
Beilstein J. Org. Chem. 2025, 21, 526–532, doi:10.3762/bjoc.21.40
Graphical Abstract
Figure 1: A: Structure of cryptophycin-52. B: Cryptophycin-52 derivatives modified with conjugation handles i...
Scheme 1: Synthesis of modified unit B derivatives. a) HNO3, H2SO4, 0 °C, 5 h, 48% (isolated as monohydrate);...
Figure 2: Molecular structure of Boc-ᴅ-Phe(4-NHMe)-OMe 7 as determined by single-crystal X-ray diffraction me...
Scheme 2: Synthesis of cryptophycin diols 24 and 25. a) EDC·HCl, DMAP, NEt3, CH2Cl2, 0 °C to rt, 22 h, 60%; b...
Scheme 3: Three-step diol–epoxide transformation starting from diols 24 and 25. a) (MeO)3CH, pyridinium p-tol...
Beilstein J. Org. Chem. 2025, 21, 286–295, doi:10.3762/bjoc.21.21
Graphical Abstract
Scheme 1: Reaction of arylamines and MBH carbonates of isatins. Reaction conditions: MBH carbonate of isatin ...
Scheme 2: Reaction of arylamines and MBH maleimides of isatins. Reaction conditions: MBH maleimide of isatin ...
Figure 1: Single crystal structure of compound 5a.
Figure 2: Single crystal structure of compound 5j.
Scheme 3: Reactions of MBH carbonates of isatins and triphenylphosphine. Reaction conditions: MBH carbonate o...
Figure 3: Single crystal structure of compound 6e.
Figure 4: Single crystal structure of compound 7a.
Figure 5: Single crystal structure of compound 8a.
Scheme 4: Proposed reaction mechanism for the various compounds.
Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6
Graphical Abstract
Scheme 1: Formation of axially chiral styrenes 3 via iminium activation.
Scheme 2: Synthesis of axially chiral 2-arylquinolines 6.
Scheme 3: Atroposelective intramolecular (4 + 2) annulation leading to aryl-substituted indolines.
Scheme 4: Atroposelective formation of biaryl via twofold aldol condensation.
Scheme 5: Strategy towards diastereodivergent formation of axially chiral oligonaphthylenes.
Scheme 6: Atroposelective formation of chiral biaryls based on a Michael/Henry domino reaction.
Scheme 7: Organocatalytic Michael/aldol cascade followed by oxidative aromatization.
Scheme 8: Atroposelective formation of C(sp2)–C(sp3) axially chiral compounds.
Scheme 9: NHC-catalyzed synthesis of axially chiral styrenes 26.
Scheme 10: NHC-catalyzed synthesis of biaxial chiral pyranones.
Scheme 11: Formation of bridged biaryls with eight-membered lactones.
Scheme 12: The NHC-catalyzed (3 + 2) annulation of urazoles 37 and ynals 36.
Scheme 13: NHC-catalyzed synthesis of axially chiral 4‑aryl α‑carbolines 41.
Scheme 14: NHC-catalyzed construction of N–N-axially chiral pyrroles and indoles.
Scheme 15: NHC-catalyzed oxidative Michael–aldol cascade.
Scheme 16: NHC-catalyzed (4 + 2) annulation for the synthesis of benzothiophene-fused biaryls.
Scheme 17: NHC-catalyzed desymmetrization of N-aryl maleimides.
Scheme 18: NHC-catalyzed deracemization of biaryl hydroxy aldehydes 55a–k into axially chiral benzonitriles 56a...
Scheme 19: NHC-catalyzed desymmetrization of 2-aryloxyisophthalaldehydes.
Scheme 20: NHC-catalyzed DKR of 2-arylbenzaldehydes 62.
Scheme 21: Atroposelective biaryl amination.
Scheme 22: CPA-catalyzed atroposelective amination of 2-anilinonaphthalenes.
Scheme 23: Atroposelective DKR of naphthylindoles.
Scheme 24: CPA-catalyzed kinetic resolution of binaphthylamines.
Scheme 25: Atroposelective amination of aromatic amines with diazodicarboxylates.
Scheme 26: Atroposelective Friedländer heteroannulation.
Scheme 27: CPA-catalyzed formation of axially chiral 4-arylquinolines.
Scheme 28: CPA-catalyzed Friedländer reaction of arylketones with cyclohexanones.
Scheme 29: CPA-catalyzed atroposelective Povarov reaction.
Scheme 30: Atroposelective CPA-catalyzed Povarov reaction.
Scheme 31: Paal–Knorr formation of axially chiral N-pyrrolylindoles and N-pyrrolylpyrroles.
Scheme 32: Atroposelective Paal–Knorr reaction leading to N-pyrrolylpyrroles.
Scheme 33: Atroposelective Pictet–Spengler reaction of N-arylindoles with aldehydes.
Scheme 34: Atroposelective Pictet–Spengler reaction leading to tetrahydroisoquinolin-8-ylanilines.
Scheme 35: Atroposelective formation of arylindoles.
Scheme 36: CPA-catalyzed arylation of naphthoquinones with indolizines.
Scheme 37: Atroposelective reaction of o-naphthoquinones.
Scheme 38: CPA-catalyzed formation of axially chiral arylquinones.
Scheme 39: CPA-catalyzed axially chiral N-arylquinones.
Scheme 40: Atroposelective additions of bisindoles to isatin-based 3-indolylmethanols.
Scheme 41: CPA-catalyzed synthesis of axially chiral arylindolylindolinones.
Scheme 42: CPA-catalyzed reaction between bisindoles and ninhydrin-derived 3-indoylmethanols.
Scheme 43: Atroposelective reaction of bisindoles and isatin-derived imines.
Scheme 44: CPA-catalyzed formation of axially chiral bisindoles.
Scheme 45: Atroposelective reaction of 2-naphthols with alkynylhydroxyisoindolinones.
Scheme 46: CPA-catalyzed reaction of indolylnaphthols with propargylic alcohols.
Scheme 47: Atroposelective formation of indolylpyrroloindoles.
Scheme 48: Atroposelective reaction of indolylnaphthalenes with alkynylnaphthols.
Scheme 49: CPA-catalyzed addition of naphthols to alkynyl-2-naphthols and 2-naphthylamines.
Scheme 50: CPA-catalyzed formation of axially chiral aryl-alkene-indoles.
Scheme 51: CPA-catalyzed formation of axially chiral styrenes.
Scheme 52: Atroposelective formation of alkenylindoles.
Scheme 53: Atroposelective formation of axially chiral arylquinolines.
Scheme 54: Atroposelective (3 + 2) cycloaddition of alkynylindoles with azonaphthalenes.
Scheme 55: CPA-catalyzed formation of axially chiral 3-(1H-benzo[d]imidazol-2-yl)quinolines.
Scheme 56: Atroposelective cyclization of 3-(arylethynyl)-1H-indoles.
Scheme 57: Atroposelective three-component heteroannulation.
Scheme 58: CPA-catalyzed formation of arylbenzimidazols.
Scheme 59: CPA-catalyzed reaction of N-naphthylglycine esters with nitrosobenzenes.
Scheme 60: CPA-catalyzed formation of axially chiral N-arylbenzimidazoles.
Scheme 61: CPA-catalyzed formation of axially chiral arylbenzoindoles.
Scheme 62: CPA-catalyzed formation of pyrrolylnaphthalenes.
Scheme 63: CPA-catalyzed addition of naphthols and indoles to nitronaphthalenes.
Scheme 64: Atroposelective reaction of heterobiaryl aldehydes and aminobenzamides.
Scheme 65: Atroposelective cyclization forming N-arylquinolones.
Scheme 66: Atroposelective formation of 9H-carbazol-9-ylnaphthalenes and 1H-indol-1-ylnaphthalene.
Scheme 67: CPA-catalyzed formation of pyrazolylnaphthalenes.
Scheme 68: Atroposelective addition of diazodicarboxamides to azaborinephenols.
Scheme 69: Catalytic formation of axially chiral arylpyrroles.
Scheme 70: Atroposelective coupling of 1-azonaphthalenes with 2-naphthols.
Scheme 71: CPA-catalyzed formation of axially chiral oxindole-based styrenes.
Scheme 72: Atroposelective electrophilic bromination of aminonaphthoquinones.
Scheme 73: Atroposelective bromination of dienes.
Scheme 74: CPA-catalyzed formation of axially chiral 5-arylpyrimidines.
Scheme 75: Atroposelective hydrolysis of biaryloxazepines.
Scheme 76: Atroposelective opening of dinaphthosiloles.
Scheme 77: Atroposelective reduction of naphthylenals.
Scheme 78: Atroposelective allylic substitution with 2-naphthols.
Scheme 79: Atroposelective allylic alkylation with phosphinamides.
Scheme 80: Atroposelective allylic substitution with aminopyrroles.
Scheme 81: Atroposelective allylic substitution with aromatic sulfinamides.
Scheme 82: Atroposelective sulfonylation of naphthylynones.
Scheme 83: Squaramide-catalyzed reaction of alkynyl-2-naphthols with 5H-oxazolones.
Scheme 84: Formation of axially chiral styrenes via sulfonylative opening of cyclopropanols.
Scheme 85: Atroposelective organo-photocatalyzed sulfonylation of alkynyl-2-naphthols.
Scheme 86: Thiourea-catalyzed atroposelective cyclization of alkynylnaphthols.
Scheme 87: Squaramide-catalyzed formation of axially chiral naphthylisothiazoles.
Scheme 88: Atroposelective iodo-cyclization catalyzed by squaramide C69.
Scheme 89: Squaramide-catalyzed formation of axially chiral oligoarenes.
Scheme 90: Atroposelective ring-opening of cyclic N-sulfonylamides.
Scheme 91: Thiourea-catalyzed kinetic resolution of naphthylpyrroles.
Scheme 92: Atroposelective ring-opening of arylindole lactams.
Scheme 93: Atroposelective reaction of 1-naphthyl-2-tetralones and diarylphosphine oxides.
Scheme 94: Atroposelective reaction of iminoquinones with indoles.
Scheme 95: Kinetic resolution of binaphthylalcohols.
Scheme 96: DKR of hydroxynaphthylamides.
Scheme 97: Atroposelective N-alkylation with phase-transfer catalyst C75.
Scheme 98: Atroposelective allylic substitution via kinetic resolution of biarylsulfonamides.
Scheme 99: Atroposelective bromo-functionalization of alkynylarenes.
Scheme 100: Sulfenylation-induced atroposelective cyclization.
Scheme 101: Atroposelective O-sulfonylation of isochromenone-indoles.
Scheme 102: NHC-catalyzed atroposelective N-acylation of anilines.
Scheme 103: Peptide-catalyzed atroposelective ring-opening of lactones.
Scheme 104: Peptide-catalyzed coupling of 2-naphthols with quinones.
Scheme 105: Atroposelective nucleophilic aromatic substitution of fluoroarenes.
Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261
Graphical Abstract
Figure 1: Classical MCRs.
Figure 2: Different scaffolds that can be formed with the Ugi adduct.
Scheme 1: Oxoindole-β-lactam core produced in a U4C-3CR.
Figure 3: Most active oxoindole-β-lactam compounds developed by Brãndao et al. [33].
Scheme 2: Ugi-azide synthesis of benzofuran, pyrazole and tetrazole hybrids.
Figure 4: The most promising hybrids synthesized via the Ugi-azide multicomponent reaction reported by Kushwa...
Scheme 3: Four-component Ugi reaction for the synthesis of novel antioxidant compounds.
Figure 5: Most potent antioxidant compounds obtained through the Ugi four-component reaction developed by Pac...
Scheme 4: Four-component Ugi reaction to synthesize β-amiloyd aggregation inhibitors.
Figure 6: The most potential β-amiloyd aggregation inhibitors generated by Galante et al. [37].
Scheme 5: Four-component Ugi reaction to obtain FATH hybrids and the best candidate synthesized.
Scheme 6: Four-component Ugi reaction for the synthesis of FATMH hybrids and the best candidate synthesized.
Scheme 7: Petasis multicomponent reaction to produce pyrazine-based MTDLs.
Figure 7: Best pyrazine-based MTDLs synthesized by Madhav et al. [40].
Scheme 8: Synthesis of BCPOs employing a Knoevenagel-based multicomponent reaction and the best candidate syn...
Scheme 9: Hantzsch multicomponent reaction for the synthesis of DHPs as novel MTDLs.
Figure 8: Most active 1,4-dihydropyridines developed by Malek et al. [43].
Scheme 10: Chromone–donepezil hybrid MTDLs obtained via the Passerini reaction.
Figure 9: Best CDH-based MTDLs as AChE inhibitors synthesized by Malek et al. [46].
Scheme 11: Replacement of the nitrogen in lactams 11 with an oxygen in 12 to influence hydrogen-bond donating ...
Scheme 12: MCR 3 + 2 reaction to develop spirooxindole, spiroacenaphthylene, and bisbenzo[b]pyran compounds.
Figure 10: SIRT2 activity of best derivatives obtained by Hasaninejad et al. [49].
Scheme 13: Synthesis of ML192 analogs using the Gewald multicomponent reaction and the best candidate synthesi...
Scheme 14: Development of 1,5-benzodiazepines via Ugi/deprotection/cyclization (UDC) approach by Xu et al. [59].
Scheme 15: Synthesis of polysubstituted 1,4-benzodiazepin-3-ones using UDC strategy.
Scheme 16: Synthetic procedure to obtain 3-carboxamide-1,4-benzodiazepin-5-ones employing Ugi–reduction–cycliz...
Scheme 17: Ugi cross-coupling (U-4CRs) to synthesize triazolobenzodiazepines.
Scheme 18: Azido-Ugi four component reaction cyclization to obtain imidazotetrazolodiazepinones.
Scheme 19: Synthesis of oxazolo- and thiazolo[1,4]benzodiazepine-2,5-diones via Ugi/deprotection/cyclization a...
Scheme 20: General synthesis of 2,3-dichlorophenylpiperazine-derived compounds by the Ugi reaction and Ugi/dep...
Figure 11: Best DRD2 compounds synthesized using a multicomponent strategy.
Scheme 21: Bucherer–Bergs multicomponent reaction to obtain a key intermediate in the synthesis of pomaglumeta...
Scheme 22: Ugi reaction to synthesize racetam derivatives and example of two racetams synthesized by Cioc et a...
Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258
Graphical Abstract
Figure 1: Example bioactive compounds containing cyclic scaffolds potentially accessible by HVI chemistry.
Figure 2: A general mechanism for HVI-mediated endo- or exo-halocyclisation.
Scheme 1: Metal-free synthesis of β-fluorinated piperidines 6. Ts = tosyl.
Scheme 2: Intramolecular aminofluorination of unactivated alkenes with a palladium catalyst.
Scheme 3: Aminofluorination of alkenes in the synthesis of enantiomerically pure β-fluorinated piperidines. P...
Scheme 4: Synthesis of β-fluorinated piperidines.
Scheme 5: Intramolecular fluoroaminations of unsaturated amines published by Li.
Scheme 6: Intramolecular aminofluorination of unsaturated amines using 1-fluoro-3,3-dimethylbenziodoxole (12)...
Scheme 7: 3-fluoropyrrolidine synthesis. aDiastereomeric ratio (cis/trans) determined by 19F NMR analysis.
Scheme 8: Kitamura’s synthesis of 3-fluoropyrrolidines. Values in parentheses represent the cis:trans ratio.
Scheme 9: Jacobsen’s enantio- and diastereoselective protocol for the synthesis of syn-β-fluoroaziridines 15.
Scheme 10: Different HVI reagents lead to different diastereoselectivity in aminofluorination competing with c...
Scheme 11: Fluorocyclisation of unsaturated alcohols and carboxylic acids to make tetrahydrofurans, fluorometh...
Scheme 12: Oxyfluorination of unsaturated alcohols.
Scheme 13: Synthesis and mechanism of fluoro-benzoxazepines.
Scheme 14: Intramolecular fluorocyclisation of unsaturated carboxylic acids. Yield of isolated product within ...
Scheme 15: Synthesis of fluorinated tetrahydrofurans and butyrolactone.
Scheme 16: Synthesis of fluorinated oxazolines 32. aReaction time increased to 40 hours. Yields refer to isola...
Scheme 17: Electrochemical synthesis of fluorinated oxazolines.
Scheme 18: Electrochemical synthesis of chromanes.
Scheme 19: Synthesis of fluorinated oxazepanes.
Scheme 20: Enantioselective oxy-fluorination with a chiral aryliodide catayst.
Scheme 21: Catalytic synthesis of 5‑fluoro-2-aryloxazolines using BF3·Et2O as a source of fluoride and an acti...
Scheme 22: Intramolecular carbofluorination of alkenes.
Scheme 23: Intramolecular chlorocyclisation of unsaturated amines.
Scheme 24: Synthesis of chlorinated cyclic guanidines 44.
Scheme 25: Synthesis of chlorinated pyrido[2,3-b]indoles 46.
Scheme 26: Chlorolactonization and chloroetherification reactions.
Scheme 27: Proposed mechanism for the synthesis of chloromethyl oxazolines 49.
Scheme 28: Oxychlorination to form oxazine and oxazoline heterocycles promoted by BCl3.
Scheme 29: Aminobromocyclisation of homoallylic sulfonamides 53. The cis:trans ratios based on the 1H NMR of t...
Scheme 30: Synthesis of cyclic imines 45.
Scheme 31: Synthesis of brominated pyrrolo[2,3-b]indoles 59.
Scheme 32: Bromoamidation of alkenes.
Scheme 33: Synthesis of brominated cyclic guanidines 61 and 61’.
Scheme 34: Intramolecular bromocyclisation of N-oxyureas.
Scheme 35: The formation of 3-bromoindoles.
Scheme 36: Bromolactonisation of unsaturated acids 68.
Scheme 37: Synthesis of 5-bromomethyl-2-oxazolines.
Scheme 38: Synthesis of brominated chiral morpholines.
Scheme 39: Bromoenolcyclisation of unsaturated dicarbonyl groups.
Scheme 40: Brominated oxazines and oxazolines with BBr3.
Scheme 41: Synthesis of 5-bromomethtyl-2-phenylthiazoline.
Scheme 42: Intramolecular iodoamination of unsaturated amines.
Scheme 43: Formation of 3-iodoindoles.
Scheme 44: Iodoetherification of 2,2-diphenyl-4-penten-1-carboxylic acid (47’) and 2,2-diphenyl-4-penten-1-ol (...
Scheme 45: Synthesis of 5-iodomethyl-2-oxazolines.
Scheme 46: Synthesis of chiral iodinated morpholines. aFrom the ʟ-form of the amino acid starting material. Th...
Scheme 47: Iodoenolcyclisation of unsaturated dicarbonyl compounds 74.
Scheme 48: Synthesis of 5-iodomethtyl-2-phenylthiazoline (87).
Beilstein J. Org. Chem. 2024, 20, 3077–3084, doi:10.3762/bjoc.20.256
Graphical Abstract
Scheme 1: Synthetic approaches to obtain the 1,5-disubstituted tetrazole-indole system and our synthetic appr...
Scheme 2: High-order multicomponent reaction for the synthesis of 1,5-disubstituted tetrazol-methanesulfonyli...
Scheme 3: Plausible reaction mechanism for the synthesis of target molecules 18a–n.
Figure 1: Differential effect of the 1,5-disubstituted tetrazole-indole hybrid compounds 18a–j on proliferati...
Beilstein J. Org. Chem. 2024, 20, 2827–2833, doi:10.3762/bjoc.20.238
Graphical Abstract
Scheme 1: Synthesis of polyfunctionalized methane derivatives through successive nucleophilic additions to th...
Scheme 2: Cyclization of 4a quenched by D2O.
Scheme 3: Plausible mechanisms for the ring closure of 4.
Scheme 4: Hydration of the ethynyl group of 4a.
Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215
Graphical Abstract
Figure 1: Triazatriangulenium cations 1a+ and 1b+.
Figure 2: Synthesis of triazatriangulenium ion pairs 2+-X− (X− = BF4−, PF6−, B(C6F5)4−, and PCCp−).
Figure 3: Single-crystal X-ray structures of (a) 2+-Cl−, (b) 2+-BF4−, (c) 2+-PF6−, (d) 2+-B(C6F5)4−, and (e) 2...
Figure 4: Hirshfeld surface analysis mapped with dnorm of closely contacted two 2+ in (a) 2+-BF4− and (b) 2+-...
Figure 5: Hirshfeld surface analysis mapped with dnorm of closely contacted ion pairs: (a) 2+-Cl−, (b) 2+-BF4−...
Figure 6: (i) Single-crystal X-ray structures and (ii) interaction energies for the pairs (a) 2+-Cl−, (b) 2+-...
Figure 7: Hirshfeld surface analysis mapped with dnorm of closely contacted ion pairs: (a) 2+-B(C6F5)4− and (...
Figure 8: (i) Single-crystal X-ray structures and (ii) interaction energies for the pairs for (a) 2+-B(C6F5)4−...
Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206
Graphical Abstract
Scheme 1: Expectation of the regio- as well as stereoselective reactions of 2.
Scheme 2: Attempts of the present epoxidation to other α,β-unsaturated esters, 1h–j.
Figure 1: Crystallographic structure of the epoxy ring-opening products by PhCH(NH2)Me (3bd) and PhCH2SH (4ba...
Scheme 3: Introduction of additional halogen atoms at the 2-position of the compound 2b.
Scheme 4: Clarification of the stereochemistry of anti,syn-8a and -7b.
Figure 2: Crystallographic structure of anti,syn-8a.
Scheme 5: Reaction of 2b with other stabilized nucleophiles.
Scheme 6: Production of 4,4,4-trifluoro-2,3-dihydroxybutanoate anti-10a.
Scheme 7: Reactions of n-C10H21MgBr-based cuprate with 13f as well as 2b with/without D2O quenching.
Figure 3: A part of 13C NMR spectra for the compounds 11a and 11a-D.
Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204
Graphical Abstract
Figure 1: Set of literature-known monocationic cyclic diaryliodonium(III) salts that were applied as XB donor...
Scheme 1: Synthesis of the iodoloisoxazolium salts 7Z: (a) 1.5 equiv 9, 0.2 equiv CuI, 2.0 equiv K2CO3, (THF)...
Figure 2: Halogen bonding dimer found in the crystal structure of 7Br. Ellipsoids are shown at 50% probabilit...
Scheme 2: Gold(I)-catalyzed cyclization of propargylic amide 11 as benchmark reaction for Au–Cl activation.
Figure 3: 1H NMR kinetics of the gold-catalyzed cyclization shown in Scheme 2. An equimolar amount of the gold comple...
Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197
Graphical Abstract
Scheme 1: a) Lewis acid activation of hypervalent iodine reagents can enhance the reactivity of these reagent...
Scheme 2: Scope and limitations of HFIP-promoted direct aziridination with iminoiodinane reagents. Conditions...
Scheme 3: Scope of nitrogen group transfer in the aziridination of aliphatic olefins. Conditions using synthe...
Scheme 4: a) The broadening of the hydroxide proton (denoted by asterisk *) of HFIP in the presence of iminoi...
Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175
Graphical Abstract
Scheme 1: Synthesis of triazolopyridinium salts [34-36].
Scheme 2: Synthesis of pyrazoles [37].
Scheme 3: Synthesis of indazoles from ketone-derived hydrazones [38].
Scheme 4: Intramolecular C(sp2)–H functionalization of aldehyde-derived N-(2-pyridinyl)hydrazones for the syn...
Scheme 5: Synthesis of pyrazolo[4,3-c]quinoline derivatives [40].
Scheme 6: Synthesis of 1,3,4-oxadiazoles and Δ3-1,3,4-oxadiazolines [41].
Scheme 7: Synthesis of 1,3,4-oxadiazoles [43].
Scheme 8: Synthesis of 2-(1,3,4-oxadiazol-2-yl)anilines [44].
Scheme 9: Synthesis of fused s-triazolo perchlorates [45].
Scheme 10: Synthesis of 1-aryl and 1,5-disubstitued 1,2,4-triazoles [49].
Scheme 11: Synthesis of 1,3,5-trisubstituted 1,2,4-triazoles [50].
Scheme 12: Alternative synthesis of 1,3,5-trisubstituted 1,2,4-triazoles [51].
Scheme 13: Synthesis of 5-amino 1,2,4-triazoles [55].
Scheme 14: Synthesis of 1-arylpyrazolines [58].
Scheme 15: Synthesis of 3‑aminopyrazoles [60].
Scheme 16: Synthesis of [1,2,4]triazolo[4,3-a]quinolines [61].·
Scheme 17: Synthesis of 1,2,3-thiadiazoles [64].
Scheme 18: Synthesis of 5-thioxo-1,2,4-triazolium inner salts [65].
Scheme 19: Synthesis of 1-aminotetrazoles [66].
Scheme 20: C(sp2)–H functionalization of aldehyde-derived hydrazones: general mechanisms.
Scheme 21: C(sp2)–H functionalization of benzaldehyde diphenyl hydrazone [68,69].
Scheme 22: Phosphorylation of aldehyde-derived hydrazones [70].
Scheme 23: Azolation of aldehyde-derived hydrazones [72].
Scheme 24: Thiocyanation of benzaldehyde-derived hydrazone 122 [73].
Scheme 25: Sulfonylation of aromatic aldehyde-derived hydrazones [74].
Scheme 26: Trifluoromethylation of aromatic aldehyde-derived hydrazones [76].
Scheme 27: Electrooxidation of benzophenone hydrazones [77].
Scheme 28: Electrooxidative coupling of benzophenone hydrazones and alkenes [77].
Scheme 29: Electrosynthesis of α-diazoketones [78].
Scheme 30: Electrosynthesis of stable diazo compounds [80].
Scheme 31: Photoelectrochemical synthesis of alkenes through in situ generation of diazo compounds [81].
Scheme 32: Synthesis of nitriles [82].
Scheme 33: Electrochemical oxidation of ketone-derived NH-allylhydrazone [83].
Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166
Graphical Abstract
Scheme 1: Pyridoindazolium salts known to date and obtained in the present work.
Scheme 2: Synthesis of S1–S3 salts using PIFA as an oxidant and the resonance structures demonstrating the el...
Figure 1: CV curves for salt S2 and corresponding amine A2 (left, Figure 1a) and salt S3 with and without diethyl malo...
Scheme 3: Redox-interconversion between diarylamines A1–A3 and N-arylpyridoindazoliums S1–S3.
Scheme 4: Electrochemical approach to pyridoindazolium salts.
Figure 2: CV curves for amine A1 without the lutidine additive (black curve) and after addition of 2 equiv (r...
Figure 3: Semi-differential CV curves for the mediators (TEMPO, bis(4-tert-butylphenyl)nitroxide and tris(4-b...
Figure 4: CV curves of bis(4-tert-butylphenyl)nitroxide (a) and TEMPO (b) with amine A3 and 2,6-lutidine adde...
Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152
Graphical Abstract
Figure 1: Steroidal spiro heterocycles with remarkable pharmacological activity.
Scheme 1: Synthesis of the spirooxetanone 2. a) t-BuOK, THF, rt, 16%.
Scheme 2: Synthesis of the 17-spirooxetane derivative 7. a) HC≡C(CH2)2CH2OTBDPS, n-BuLi, THF, BF3·Et2O, −78 °...
Scheme 3: Pd-catalyzed carbonylation of steroidal alkynols to produce α-methylene-β-lactones at C-3 and C-17 ...
Scheme 4: Catalyst-free protocol to obtain functionalized spiro-lactones by an intramolecular C–H insertion. ...
Scheme 5: One-pot procedure from dienamides to spiro-β-lactams. a) 1. Ac2O, DMAP, Et3N, CH2Cl2, 2. malononitr...
Scheme 6: Spiro-γ-lactone 20 afforded from 7α-alkanamidoestrone derivative 17. a) HC≡CCH2OTHP, n-BuLi, THF, –...
Scheme 7: Synthesis of the 17-spiro-γ-lactone 23, a key intermediate to obtain spironolactone. a) Ethyl propi...
Scheme 8: Synthetic pathway to obtain 17-spirodihydrofuran-3(2H)-ones from 17-oxosteroids. a) 1-Methoxypropa-...
Scheme 9: One-pot procedure to obtain 17-spiro-2H-furan-3-one compounds. a) NaH, diethyl oxalate, benzene, rt...
Scheme 10: Synthesis of 17-spiro-2H-furan-3-one derivatives. a) RCH=NOH, N-chlorosuccinimide/CHCl3, 99%; b) H2...
Scheme 11: Intramolecular condensation of a γ-acetoxy-β-ketoester to synthesize spirofuranone 37. a) (CH3CN)2P...
Scheme 12: Synthesis of spiro 2,5-dihydrofuran derivatives. a) Allyl bromide, DMF, NaH, 0 °C to rt, 93%; b) G-...
Scheme 13: First reported synthesis of C-16 dispiropyrrolidine derivatives. a) Sarcosine, isatin, MeOH, reflux...
Scheme 14: Cycloadducts 47 with antiproliferative activity against human cancer cell lines. a) 1,4-Dioxane–MeO...
Scheme 15: Spiropyrrolidine compounds generated from (E)-16-arylidene steroids and different ylides. a) Acenap...
Scheme 16: 3-Spiropyrrolidines 52a–c obtained from ketones 50a–c. a) p-Toluenesulfonyl hydrazide, MeOH, rt; b)...
Scheme 17: 16-Spiropyrazolines from 16-methylene-13α-estrone derivatives. a) AgOAc, toluene, rt, 78–81%.
Scheme 18: 6-Spiroimidazolines 57 synthesized by a one-pot multicomponent reaction. a) R3-NC, T3P®, DMSO, 70 °...
Scheme 19: Synthesis of spiro-1,3-oxazolines 60, tested as progesterone receptor antagonist agents. a) CF3COCF3...
Scheme 20: Synthesis of spiro-1,3-oxazolidin-2-ones 63 and 66a,b. a) RNH2, EtOH, 70 °C, 70–90%; b) (CCl3O)2CO,...
Scheme 21: Formation of spiro 1,3-oxazolidin-2-one and spiro 2-substituted amino-4,5-dihydro-1,3-oxazoles from ...
Scheme 22: Synthesis of diastereomeric spiroisoxazolines 74 and 75. a) Ar-C(Cl)=N-OH, DIPEA, toluene, rt, 74 (...
Scheme 23: Spiro 1,3-thiazolidine derivatives 77–79 obtained from 2α-bromo-5α-cholestan-3-one 76. a) 2-aminoet...
Scheme 24: Method for the preparation of derivative 83. a) Benzaldehyde, MeOH, reflux, 77%; b) thioglycolic ac...
Scheme 25: Synthesis of spiro 1,3-thiazolidin-4-one derivatives from steroidal ketones. a) Aniline, EtOH, refl...
Scheme 26: Synthesis of spiro N-aryl-1,3-thiazolidin-4-one derivatives 91 and 92. a) Sulfanilamide, DMF, reflu...
Scheme 27: 1,2,4-Trithiolane dimers 94a–e selectively obtained from carbonyl derivatives. a) LR, CH2Cl2, reflu...
Scheme 28: Spiro 1,2,4-triazolidin-3-ones synthesized from semicarbazones. a) H2O2, CHCl3, 0 °C, 82–85%.
Scheme 29: Steroidal spiro-1,3,4-oxadiazoline 99 obtained in two steps from cholest-5-en-3-one (97). a) NH2NHC...
Scheme 30: Synthesis of spiro-1,3,4-thiadiazoline 101 by cyclization and diacetylation of thiosemicarbazone 100...
Scheme 31: Mono- and bis(1,3,4-thiadiazolines) obtained from estrane and androstane derivatives. a) H2NCSNHNH2...
Scheme 32: Different reaction conditions to synthesize spiro-1,3,2-oxathiaphospholanes 108 and 109.
Scheme 33: Spiro-δ-lactones derived from ADT and epi-ADT as inhibitors of 17β-HSDs. a) CH≡C(CH2)2OTHP, n-BuLi,...
Scheme 34: Spiro-δ-lactams 123a,b obtained in a five-step reaction sequence. a) (R)-(+)-tert-butylsulfinamide,...
Scheme 35: Steroid-coumarin conjugates as fluorescent DHT analogues to study 17-oxidoreductases for androgen m...
Scheme 36: 17-Spiro estradiolmorpholinones 130 bearing two types of molecular diversity. a) ʟ- or ᴅ-amino acid...
Scheme 37: Steroidal spiromorpholinones as inhibitors of enzyme 17β-HSD3. a) Methyl ester of ʟ- or ᴅ-leucine, ...
Scheme 38: Steroidal spiro-morpholin-3-ones achieved by N-alkylation or N-acylation of amino diols 141, follow...
Scheme 39: Straightforward method to synthesize a spiromorpholinone derivative from estrone. a) BnBr, K2CO3, CH...
Scheme 40: Pyrazolo[4,3-e][1,2,4]-triazine derivatives 152–154. a) 4-Aminoantipyrine, EtOH/DMF, reflux, 82%; b...
Scheme 41: One-pot procedure to synthesize spiro-1,3,4-thiadiazine derivatives. a) NH2NHCSCONHR, H2SO4, dioxan...
Scheme 42: 1,2,4-Trioxanes with antimalarial activity. a) 1. O2, methylene blue, CH3CN, 500 W tungsten halogen...
Scheme 43: Tetraoxanes 167 and 168 synthesized from ketones 163, 165 and 166. a) NaOH, iPrOH/H2O, 80 °C, 93%; ...
Scheme 44: 1,2,4,5-Tetraoxanes bearing a steroidal moiety and a cycloalkane. a) 30% H2O2/CH2Cl2/CH3CN, HCl, rt...
Scheme 45: Spiro-1,3,2-dioxaphosphorinanes obtained from estrone derivatives. a) KBH4, MeOH, THF or CH2Cl2; b)...
Scheme 46: Synthesis of steroidal spiro-ε-lactone 183. a) 1. Jones reagent, acetone, 0 °C to rt, 2. ClCOCOCl, ...
Scheme 47: Synthesis of spiro-2,3,4,7-tetrahydrooxepines 185 and 187 derived from mestranol and lynestrenol (38...
Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151
Graphical Abstract
Scheme 1: Targeted natural products and key enzymatic transformations in the chemo-enzymatic total syntheses ...
Scheme 2: Biosynthetic pathway to brassicicenes in Pseudocercospora fijiensis [14]. (A) Cyclization phase catalyz...
Scheme 3: Chemo-enzymatic total synthesis of cotylenol (1) and brassicicenes. (A) Chemical cyclization phase....
Scheme 4: (A) Biosynthetic pathway for trichodimerol (2) in Penicillium chrysogenum. (B) Chemo-enzymatic tota...
Scheme 5: (A) Proposed biosynthetic pathway for chalcomoracin (3) in Morus alba. (B) Outline of the biosynthe...
Scheme 6: (A) Chemo-enzymatically synthesized natural products by using the originally identified MaDA. (B) M...
Scheme 7: Proposed biosynthetic mechanism of tylactone (4) in Streptomyces fradiae.
Scheme 8: (A) Chemical synthesis and cascade enzymatic transformations of cyclization precursors. (B) Late-st...
Scheme 9: Proposed biosynthetic mechanism of saframycin A (5) in Streptomyces lavendulae.
Scheme 10: (A) Chemo-enzymatic total synthesis of saframycin A (5) and jorunnamycin A (103). (B) Chemo-enzymat...
Beilstein J. Org. Chem. 2024, 20, 1671–1676, doi:10.3762/bjoc.20.148
Graphical Abstract
Scheme 1: Build and release approach for the functionalization of simple precursors. a) General overview. b) ...
Scheme 2: Modularity of the Norrish–Yang cyclization for the synthesis of azetidines.
Scheme 3: Ring-opening reactions using electron-deficient ketones and boronic acids.
Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142
Graphical Abstract
Scheme 1: Illustration of the reversible visible-light-controlled ring closure and thermal-driven ring-openin...
Scheme 2: Synthetic pathway to DAn.
Figure 1: UV–vis-absorption-spectral changes of DAn in THF solution (20 μM). (a) DA11, (c) DA7, (e) DA6 solut...
Figure 2: UV–vis absorption spectra of DAn in aqueous solution (43 μM). (a) DA11 (inset: enlarged 400–480 nm ...
Figure 3: TEM images of freshly prepared aqueous solutions before irradiation of (a) DA11 (0.25 wt %, 4.1 mM)...
Figure 4: Photograph of a freshly prepared aqueous DA11 solution (82.0 mM) ejected into a shallow pool of CaCl...
Figure 5: Photographs of macroscopic soft scaffolds prepared from aqueous solutions of (a) DA11 (32.9 mM), (c...
Figure 6: Macroscopic soft DAn scaffolds fabricated by the shear-flow method. Images taken during fluorescenc...
Beilstein J. Org. Chem. 2024, 20, 1412–1420, doi:10.3762/bjoc.20.123
Graphical Abstract
Figure 1: Representative examples of relevant N-fused heterocycles.
Scheme 1: Different acid-catalyzed six-membered ring cyclizations.
Scheme 2: Substrate scope for the assembly of suitably N-3-functionalized (thio)hydantoins 4a–r. aDCM was uti...
Scheme 3: Substrate scope of the iron(III)-catalyzed synthesis of functionalized heterocyclic N,O-aminals 5a–r...
Scheme 4: Proposed mechanism for the formation of N,O-aminals 5 and hemiaminals 6.
Scheme 5: Control mechanistic experiments.
Beilstein J. Org. Chem. 2024, 20, 1189–1197, doi:10.3762/bjoc.20.101
Graphical Abstract
Scheme 1: Biosynthesis of (A) germacrene A and (B) hedycaryol from FPP. Here the abbreviations represent, FPP...
Figure 1: 6-6 and 5-7 bicyclic carbocations formed by protonation and cyclization of germacrene A and hedycar...
Figure 2: Bar plot for the relative free energies of germacrene A and hedycaryol carbocations relative to car...
Figure 3: NCI plot for A (left) and B (right). Blue corresponds to repulsive and yellow represents slightly a...
Figure 4: NCI plots for F and H hedycaryol cations. The C+···OH distances (Å) are shown in black.
Figure 5: Correlation plot relating between the stability of hedycaryols (ΔΔEe) and C+···OH bond distances.
Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97
Graphical Abstract
Figure 1: Neutral, closed-shell resonance forms for pentacene highlighting Clar aromatic sextets (see [1]) and t...
Figure 2: The only neutral, closed-shell resonance form for 5-ring isotetracenofuran with its highly delocali...
Figure 3: DFT calculated HOMO–LUMO gaps of acenes and isoacenofurans performed at the B3LYP/6-311+G(d,p)//B3L...
Figure 4: A structural rendering of 1,3-dimesitylisobenzofuran showing the requirement for non-planar mesityl...
Scheme 1: Synthesis of 1,3-diarylisobenzofurans 3 and 23.
Figure 5: UV–vis (top) and fluorescence (middle) spectra for 10−6 M solutions of 1,3-diarylisobenzofurans 2, 3...
Figure 6: Calculated HOMO and LUMO orbitals for parent isobenzofuran (1) and 1,3-diarylisobenzofuran derivati...
Figure 7: UV–vis spectra calculated for 1,3-diarylisobenzofuran derivatives 1, 2, 3, 23, 24 and 25 using a DF...
Figure 8: UV–vis spectra for the reactions of 2 (top) and 3 (bottom) with a 7000-fold excess of DMAD in CH2Cl2...
Scheme 2: Reactions between 1,3-diarylisobenzofurans 2, 3 and 23 and DMAD to produce Diels–Alder adducts 26, ...
Scheme 3: Synthesis of 1,3-dimesitylisobenzofuran (3).
Scheme 4: Synthesis of 1,2-phenylenebis(mesitylmethanone) (21).
Scheme 5: Synthesis of 1,2-phenylenebis((2,4,6-triethylphenyl)methanone) (22).
Scheme 6: Synthesis of 1,3-bis(2,4,6-triethylphenyl)isobenzofuran (23).
Scheme 7: Synthesis of dimethyl 1,4-diphenyl-1,4-dihydro-1,4-epoxynaphthalene-2,3-dicarboxylate (26).
Scheme 8: Synthesis of dimethyl 1,4-dimesityl-1,4-dihydro-1,4-epoxynaphthalene-2,3-dicarboxylate (27).